Space Shuttle to Receive Emegency Repairs

Tycow writes "The BBC are reporting that Discovery needs emergency repairs - dangling material has been spotted on the belly of the shuttle, and NASA are worried they could cause overheating on re-entry. 'Nasa is concerned the dangling material - called gap fillers - could cause part of the shuttle to overheat as it re-enters the atmosphere.The type of repairs being planned have never been conducted by astronauts on a spacewalk before.'"

Comments

Re:Paranoia.

[rhadamanthus]

NO. Boundary layer transition is not a very well understood phenomenon to begin with, and in this case you pushing the limits of both flight experience and analytical capability. Going from laminar to turbulent flow above mach 18 results in some very serious heating, ultimately effecting not just the thermal system, but also the structural margins.

Most importantly, this trip would spill over the side of vehicle and run down streamlines into the wing leading edge. Analysts put the increased heat loads even in a "best case" situation at 80% increase. At those temperatures (almost 3300F), the SiC coating will start to degrade. Dispersion in the entry tajectory could lead to an additional 150F. At that temperature the SiC will ablate, exposing the carbon-carbon substrate. It will oxidize and the temperature will skyrocket to 4000F. At that temp kiss the wing goodbye.

That all being said, I think it could make it down - the uncertainty in this situation is increasing conservatism - but I sure as hell won't take that risk when the EVA is quick and relatively simple.